Airbag for a vehicle occupant restraint system and method for folding an airbag for a vehicle occupant restraint system

ABSTRACT

An airbag for a vehicle occupant restraining system of a motor vehicle is provided. The airbag comprises a pre-folded portion, which comprises at least two subsections of the airbag, of which the one subsection is folded about a folding line via bend folding to an inner side of the other subsection facing the vehicle interior space in the mounted and inflated status of the airbag. The folded subsection is formed such that it extends in the mounted and inflated status of the airbag beyond a door balustrade of a vehicle longitudinal side. The airbag further comprises a roll folded portion, which comprises the pre-folded portion, wherein the roll folded portion is formed by rolling up the airbag to an outer side of the airbag facing in the mounted and inflated status of the airbag a vehicle longitudinal side.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102014 212 238.4 filed on Jun. 25, 2014, the entirety of which isincorporated by reference herein.

BACKGROUND

The invention relates to an airbag for a vehicle occupant restraintsystem and a method for folding an airbag for a vehicle occupantrestraint system.

Head protection side airbags (HSAB—head side airbags) are known from theprior art, which extend in the inflated status along a vehiclelongitudinal side. Such airbags are in particular dimensioned such thatthey extend in the inflated status at least with a section downwards(towards the vehicle floor) beyond a door balustrade of the vehiclelongitudinal side. This serves to prevent a moving of the airbags duringan accident out of a window of the vehicle since already a partialmovement of the airbags would be accompanied with a substantialdeterioration of its protective effect. An airbag extending beyond thedoor balustrade is described for instance in U.S. Pat. No. 7,775,553 B2.

It is furthermore known to fold at least a lower area of the headprotection side airbag with a roll folding towards the vehiclelongitudinal side (outboard). This has the effect that the airbagsunroll from the vehicle longitudinal side when introducing gas such thatthey can unfold better between a vehicle occupant being close to thevehicle longitudinal side and the vehicle longitudinal side. Suchairbags folded by outboard roll folding can unfold in particular betweena head of the vehicle occupant being close to a side window or evenlaying against the side window (so called head-on-glass-case). Such anairbag is disclosed for instance in U.S. Pat. No. 6,851,707 B2. Theoutboard roll folding reinforces however the tendency of the airbags tomove out of a broken side window in the course of an accident.

SUMMARY

An object to be solved by the invention is to provide an airbag withbetter protective effect also for a vehicle occupant not being in ausual sitting position and over a longer period after activation of theairbag as well as to provide a corresponding method for folding anairbag.

This problem is solved by providing an airbag with the features asdescribed herein and providing a method for folding an airbag with thefeatures as described herein.

Accordingly an airbag for a vehicle occupant restraint system of a motorvehicle is provided with

-   -   a pre-folded portion, which comprises at least two subsections        of the airbag of which one is folded about a folding line to a        an inner side of the other sub-sections facing the motor vehicle        interior space in a mounted and inflated status of the airbag,    -   wherein the folded subsection is formed such that it extends in        the mounted and inflated status of the airbag beyond a door        balustrade of a vehicle longitudinal side; and    -   a roll folded portion, which comprises the pre-folded portion,        wherein    -   the roll folded portion is formed by rolling up the airbag to an        outer side of the airbag facing a vehicle longitudinal side in        the mounted and inflated status of the airbag, wherein    -   the folding line is positioned such that the pre-folded portion        extends at least in a section of the airbag (i.e. in a cross        section of the folded airbag oriented vertical to the main        extension direction of the airbag) over the complete roller        folded portion.

In other words, the airbag according to the invention comprises aportion which is formed by a combination of a bend folding towards thevehicle interior space (“inboard” folding) and the roll foldingconducted towards a vehicle outer side (“outboard” roll folding). Theroll folding provides in particular that the airbag can unfold alsobetween a vehicle occupant being close to the vehicle longitudinal sideand the vehicle longitudinal side. An unrolling of the airbag out of awindow of the vehicle longitudinal side is however counteracted by thepre-folding (flapping) of the airbag present in the roll folded portion.

The height of the folded sub-section (i.e. its expansion transvers tothe folding line) of the airbag is dimensioned such that the pre-foldedportion of the airbag extends at least in a section of the airbag (forinstance in a front and/or a back section) over the complete roll foldedportion, i.e. at least in a section of the airbag the complete rollfolded portion comprises at least two sub-sections of the airbag foldedon top of each other. The folded sub-section forms in the mounted andinflated status of the airbag a lower portion of the airbag (facing thevehicle floor).

The bend folding of the airbag beforehand of the roll folding and thelarge height of the folded sub-section effect that after unrolling ofthe airbag or in a later stadium of the unrolling of the airbag thefolded subsection is at least partially on an inner side of the airbagand thus moves coming from the vehicle interior space towards the doorbalustrade and/or a section of the vehicle side structure beingunderneath the door balustrade and in particular comes to a stop there.

Furthermore the folded sub-section (i.e. the lower portion of theairbag) is filled due to a throttle effect of the pre-folding (the bendof the pre-folded portion acts as a throttle) only late after anactivation of the airbag, in particular only in the final phase of theunfolding of the roll folded portion. Thereby it can be avoided that thelower sub-section of the airbag is pushed in direction of the vehiclelongitudinal side and possibly out of a side window due to a prematurefilling of the folded lower sub-section even before a complete unrollingof the airbag.

Accordingly, the airbag according to the invention counteracts amovement of the airbag and thus of the vehicle occupant to be protectedout of the window of the vehicle longitudinal side (“ejectionmitigation”—avoiding an ejection).

The combination of “inboard” pre-folded (“inboard” bend folding) and“outboard” roll folding means in particular that the folded sub-sectionof the pre-folded portion of the airbag is folded clockwise orcounterclockwise about the folding line, looked at from a front to aback end of the folding line (wherein the “front end”—in respect to themounted status of the airbag in the vehicle—is closer to the vehiclefront than the “back end”), wherein the roll folded area is formed byrolling up the airbag—looked at from a front side of the airbag (i.e. aside of the airbag facing the vehicle front)—is formed counterclockwise,if the folded sub-section of the pre-folded portion is folded clockwise,and by rolling up the airbag clockwise, if the sub-section of thepre-folded area is folded counterclockwise.

In case of an airbag, which is to be arranged on a right vehiclelongitudinal side (looked at from the vehicle front), the roll foldingoccurs by rolling up the lower, pre-folded portion of the airbagcounterclockwise (looked at from a front side of the airbag or from thevehicle front), while the pre-folding beforehand of the roll folding iscarried out clockwise about the folding line. In case of the airbag tobe arranged on the left vehicle longitudinal side the roll foldingoccurs accordingly vice versa clockwise and the pre-foldingcounterclockwise.

According to an embodiment of the invention the pre-folded portion ofthe airbag does not end with the roll folded portion, but extends beyondthe roll folded portion. In this variant the (folded) airbag comprisesthus also a section outside of the roll folded portion, in which atleast two sub-sections of the airbag are folded on top of each other.

It is also conceivable that a zick-zack folded portion is adjacent tothe roll folded portion. For instance the pre-folded portion ends at thebeginning of the zick-zack folded portion. The zick-zack folded portioncomprises for instance multiple folding lines, wherein the pre-foldedportion extends up to the folding line which is closest to the rollfolded portion. It is however also possible that the pre-folded portionextends into the zick-zack folded portion.

In another variant of the invention the pre-folded portion of the airbagis formed by folding the airbag along multiple folding lines such thatthe pre-folded portion comprises at least three sub-sections of theairbag folded on top of each other.

The airbag is formed in particular by two airbag layers connected toeach other along at least one circumferential seam such that thepre-folded portion comprises at least four sections of the airbag layersfolded on top of each other.

It is also possible that the two airbag layers are connected to eachother in a portion, which continues at least approximately along thefolding line. For instance, the connection of the airbag layers occursvia a tear seam and/or a glue seam via which the sections of the innerside of the airbag layers are glued together.

The pre-folded portion of the airbag can extend at least essentiallyover the complete length of the airbag. The “length of the airbag” isthe extension of the airbag in a main extension direction, i.e. forinstance in respect to the mounted status in the vehicle and theinflated status of the airbag according to its length along the vehiclelongitudinal direction.

For instance the folding line of the pre-folded portion and a roll axisof the roll folding continue at least approximately parallel to eachother. In particular the folding line and the roll axis are orientedparallel to the main extension direction of the airbag, i.e. forinstance along the vehicle longitudinal direction.

It is however also conceivable that the folding line and a roll axis ofthe roll folding are oriented to each other in an angle. The roll axisis for instance aligned parallel to the main extension direction of theairbag, while the folding line is oriented in an angle to the mainextension direction. In this case the pre-folded portion extends inparticular only over a part of the length of the airbag.

It is also possible that the airbag comprises two pre-folded portions(e.g. distanced from each other), which comprise in each case asubsection of the airbag folded about a folding line, wherein thefolding lines of the pre-folded portions are oriented to each other forinstance at an angle.

The airbag according to the invention is for instance a side airbag,which extends along a vehicle longitudinal side in the vehicle mountedand inflated status. It is in particular the previous mentioned headprotection side airbag.

The invention relates also to a method for folding an airbag of avehicle occupant restraint system for a motor vehicle with the steps:

-   -   providing an evenly spread airbag;    -   generating a pre-folded portion of the airbag by folding a        subsection of the airbag about a folding line to an inner side        of another subsection of the airbag facing the vehicle interior        space in the mounted and inflated status of the airbag such that        the folded portion comprises at least two subsections of the        airbag,    -   wherein the folded subsection is formed such that it extends        beyond a door balustrade of a vehicle longitudinal side in the        mounted and inflated status of the airbag, and    -   generating a roll folded portion of the airbag which comprises        the pre-folded portion, by rolling up the airbag to an outer        side of the airbag facing a vehicle longitudinal side in the        mounted and inflated status of the airbag, wherein    -   the folding line is positioned such that the pre-folded portion        extends at least in a section of the airbag over the complete        roll folded portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following by means of examples withreference to the figures in more detail.

FIGS. 1A-1D a side airbag in cross section for different steps offolding the airbag in a method according to an embodiment of theinvention.

FIGS. 2A-2C different stages of unfolding of an airbag folded accordingto FIGS. 1A-1D and mounted in a vehicle.

FIG. 3 a perspective view of a side airbag in an intermediate statusduring folding according to the method of the invention.

FIG. 4 a side airbag in an intermediate status during folding aftermodifying the method according to the invention.

FIGS. 5A-5D Variants of the pre-folding of the method for folding anairbag according to the invention.

FIG. 6 a top view onto a side airbag according to an embodiment of theinvention in unfolded status.

DETAILED DESCRIPTION

FIG. 1A shows a cut through an evenly spread airbag in form of a sideairbag 1, which is going to be arranged in the vehicle such that itextends as a head protective airbag along a vehicle longitudinal side,i.e. it is a head side airbag (HSAB). The cut shown in FIG. 1 continuesin a plane, which is oriented vertical to the main extension directionof the airbag, i.e. in respect to the mounted status in the vehiclealong a plane, which continues parallel to a plane spanned through thevehicle cross and vehicle height direction (wherein the airbag is lookedat from the vehicle front).

The side airbag 1 comprises a lower portion 11 a, which—regarding the inthe vehicle mounted and unfolded status of the airbag 1—faces thevehicle floor. The lower portion 11 a is folded via bend folding andforms a pre-folded portion 11 (FIG. 1B). Above the portion 11 a aportion 13 a of the airbag 1 extends, which is folded via zick-zackfolding in order to form a zick-zack folded portion 13, as illustratedin FIG. 1B. An inner side 14 of the side airbag 1 will extend in theunfolded status of the side airbag 1 facing the vehicle interior spacewhile an outer side 15 facing away from the side 14 is oriented suchthat it will face a vehicle longitudinal side.

In order to generate the pre-folded portion 11 a lower sub-section 111of the side airbag 1, which comprises a lower edge section 16 of theairbag 1, is folded along a folding line F until it extends parallel toa further sub-section 112 being above the sub-section 111 and joiningthe sub-section 111 and (looked at vertical to the extension plane ofthe side airbag 1) is arranged adjacent (and namely on an inner side ofthe sub-section 112 facing the vehicle interior space; compare FIG. 1B).It is conceivable that (although this is not imperative) the lowerfolded sub-section 111 rests against the upper sub-section 112.

The folding of the lower sub-section 111 occurs thus to an inner side ofthe upper sub-section 112, i.e. in respect to FIG. 1A counterclockwiseabout the folding line F (bend line). After folding the lowersub-section 111 the sub-sections 111, 112 form the pre-folded portion11, i.e. the pre-folded portion 11 is the portion of the side airbag 1in which the two sub-sections 111, 112 connected to each other via thefolding line F, are arranged side by side. Accordingly the extension(heights vertical to folding line F) of the pre-folded portion 11 isdetermined by the extension of the folded lower subsection 111, i.e. bythe position of the folding line F.

After generating the pre-folded portion 11 the side airbag 1 is providedwith a roll folding. Thereby the side airbag 1 is rolled up from a loweredge, in which the folding line F continues, of the pre-folded portion11 upwards (towards the portion 13 a to be folded via zick-zack folding)and namely to the outer side 15 of the side airbag 1, i.e. in form of anoutboard folding. By rolling up the side airbag 1 a roll folded portion12 is formed, which is on an outer side of the non-rolled upper portion(approximately of the portion 13 a) of the side airbag 1.

Due to the outboard roll folding a middle axis R and the lower edge ofthe pre-folded portion 11 is in particular located about the foldingline F on an outer side of the non-rolled and not yet folded upperportion of the side airbag 1 (compare FIG. 1C), i.e. at the beginning ofthe outboard roll folding the lower edge of the pre-folded portion 11 ismoved to an outer side (which faces a vehicle longitudinal side in themounted status of the airbag) of the sub-section 112 and the not yetfolded upper portion of the side airbag 1. The outboard roll folding hasthe advantage that the airbag can unfold easier also between a vehicleoccupant (in particular its head) being close to a vehicle sidestructure (for instance a window plane) and the vehicle side structure.

The pre-folded portion 11 is dimensioned such (i.e. the folding line Fis positioned such) that it extends over the complete roll foldedportion 12 wherein an end 150 of the pre-folded portion 11 coincideswith an end of the roll folded portion 12. In other words the completeroll folded portion 12 comprises the sub-sections 111, 112 of thepre-folded portion 11 arranged adjacent to each other.

After obtaining the roll folded portion 12 the upper section 13 a of theside airbag 1 is folded via zick-zack folding wherein a zick-zack foldedportion 13 is generated (FIG. 1D).

The zick-zack folded portion 13 follows the roll folded portion 12 andcomprises a first and a second folding line Z1, Z2. The roll foldedportion 12 extends up to the first folding line Z1 of the zick-zackfolded portion 13, wherein the first folding line Z1 is closer to theroll folded portion 12 than the second folding line Z2. It is of courseconceivable that the zick-zack folded portion 13 has more than twofoldings (i.e. more than two folding lines) and/or that the pre-foldedportion 11 extends beyond the first folding line Z1.

When activating the side airbag 1, i.e. after activating a gas generatorprovided for filling the side airbag 1 (not shown), at first the upperportion, in particular the zick-zack folded portion 13, of the sideairbag 1 is filled with gas such that initially the portion 13 isessentially unfolded (FIG. 2A). Subsequently the roll folded portion 12(FIG. 2B) unfolds (unrolls), namely with a unroll movementcounterclockwise (in respect to FIG. 2A and the middle axis R movingdownwards).

The (height) length of the lower sub-section 111 is moreover dimensionedsuch that after the unfolding of the zick-zack folded portion 13 an end1111 of the lower folded sub-section 111 is on the inner side 14 of thezick-zack folded portion 13, i.e. on a side of the side airbag 1 facinga vehicle interior space 200. Since the folded sub-section 111 is bendfrom the upper sub-section 112 about the folding line F the foldedsub-section 111 fills with a time delay (the bend along the folding lineF acts as a throttle). This entails that the folded sub-section 111 isessentially non-filled during the unfolding of the roll folded portion12 and remains thus pressureless whereby it experiences no force whichwould move it outwards (to the left side of the airbag 1 regarding FIG.2B), i.e. in direction of the vehicle longitudinal side. Only when theroll folded portion 12 is predominantly or almost completely unrolled,the folded sub-section 111 is also filled. Since at least the end 1111of the sub-section 111 is positioned however on an inner side of theairbag 1 (for instance the sub-section 112) the sub-section 111 will hitagainst an inner side of a door balustrade coming from the vehicleinterior space and can thus not move outwards through a (for instancebroken) side window of the vehicle (FIG. 2C).

FIG. 3 shows a perspective view of a side airbag 1 after obtaining thepre-folded portion 11 by folding the lower sub-section 111 to an innerside of the side airbag 1 about the folding line F. In the example ofFIG. 3 the folding line F continues along the main extension directionof the side airbag 1, wherein the folded sub-section 111 extendsessentially over the complete length (along the main extensiondirection) of the side airbag 1.

In a next step the folded portion 11 would be folded per roll folding toan outer side of the side airbag 1 and optionally also per zick-zackfolding (corresponding to FIGS. 1C and 1D). The roll folding is carriedout along a roll axis moving upwards, which continues at leastapproximately parallel to the folding line F.

In the embodiment of FIG. 4 a front pre-folded portion 110 and a backpre-folded portion 120 is generated instead of one single pre-foldedportion 11. The front pre-folded portion 110 is obtained by folding afront sub-section 111 a of the side airbag 1 along a folding line F1oriented inclined to a main extension direction of the side airbag 1.The back folded portion 120 is generated by folding a back sub-section111 b of the side airbag 1 about a folding line F2 continuing also in anangle to the main extension direction of the side airbag 1. The foldinglines F1, F2 are oriented to each other also in an angle, wherein theycontinue towards each other looked at from an upper edge of the sideairbag 1.

As in the previous embodiments a roll folding of the airbag 1 followsthe generation of the pre-folded portions 110, 120. Said roll foldingoccurs in particular by rolling up the side airbag 1 from bottom to top(i.e. vertical to the main extension direction of the side airbag 1 orabout a roll axis oriented parallel to the main extension direction ofthe side airbag 1). A middle section of the side airbag 1 between thepre-folded portions 110, 120 is not pre-folded in this embodiment.Accordingly, no pre-folded portion is located in said section of theside airbag 1, which extends into the roll-folded portion. However, thepre-folded portions 110, 120 are provided such that they extend in eachcase into the roll folded portion and at least partially over thecomplete roll folded portion.

FIGS. 5A-5D show further variants of obtaining the pre-folded portion 11of the side airbag. According to FIG. 5A the pre-folded portion 11 isgenerated by folding two sub-sections 111, 113 along two folding linesF, F′ to an inner side of the initial upper sub-section 112.Accordingly, the pre-folded portion 11 comprises three sub-sections111-113 of the side airbag 1 adjoining each other (e.g. being on top ofeach other).

FIG. 5B resembles FIG. 5A, wherein however the third sub-section 113 isprovided longer and comprises in particular at least approximately alength, which corresponds to the length of the first and secondsub-sections 111, 112.

According to FIG. 5C the pre-folded section 11 is formed by carrying outa three times folding (along three folding lines F, F′, F″) such thatfour sub-sections 111-114 of the side airbag 1 being on top of eachother are formed. It is similar also in FIG. 5D wherein however thelength of the inner sub-sections 113, 114 (being between thesub-sections 111, 112) is smaller compared to FIG. 5C.

FIG. 6 relates to a further embodiment of the invention. Accordingly,the side airbag 1 is provided along the folding line F with a glue seam20 (e.g. in form of a silica seam) which connects the inner sides of twoairbag layers of the airbag 1 to each other. The glue seam 20 providesthat the inflation of the lower sub-section 111 of the side airbag 1folded about the folding line F is further delayed since the glue seam20 has to be ripped open only by the pressure of the gas flowing intothe airbag. This glue seam 20 could be provided with a through openingor with multiple through openings for adjusting the delay time. It isalso conceivable that instead of a glue seam a tear seam is provided,which can be reinforced by a seam tape.

LIST OF REFERENCES

1 Side airbag

11, 110, 120 Pre-folded portion

11 a Portion to be pre-folded

12 Roll folded portion

13 Zick-zack folded portion

13 a Zick-zack portion to be folded

14 Inner side

15 Outer side

16 Lower edge

20 Glue seam

111, 111 a, 111 b Lower sub-section

112 Upper sub-section

113 Third sub-section

114 Forth sub-section

150 End of pre-folded portion

200 Vehicle interior space

1111 End of upper sub-section

F, F′, F″ Folding line

R Middle axis of roll folded portion

1. An airbag for a vehicle occupant restraint system of a motor vehiclecomprising a pre-folded portion which comprises at least two subsectionsof the airbag of which one of the subsections is folded about a foldingline via bend folding to an inner side of the other subsections facing amotor vehicle interior space in a mounted and inflated status of theairbag, wherein the folded subsection is formed such that it extends ina mounted and inflated status of the airbag beyond a door balustrade ofa vehicle longitudinal side; and a roll folded portion, which comprisesthe pre-folded portion, wherein the roll folded portion is formed byrolling up the airbag to an outer side of the airbag facing a vehiclelongitudinal side in the mounted and inflated status of the airbag,wherein the folding line is positioned such the pre-folded portionextends at least in a section of the airbag over the complete rollfolded portion.
 2. The airbag according to claim 1, wherein the foldedsubsection is folded about the folding line, looked at from a front to aback end of the folding line, clockwise or counterclockwise, wherein theroll folded portion is formed by rolling the airbag counterclockwise,looked at from a front side of the airbag, if the folded subsection isfolded clockwise, and by rolling the airbag clockwise, if the foldedsubsection is folded counterclockwise.
 3. The airbag according to claim1, wherein the pre-folded portion extends beyond the roll foldedportion.
 4. The airbag according to claim 1, wherein a zick-zack foldedportion is adjacent to the roll folded portion.
 5. The airbag accordingto claim 4, wherein the pre-folded portion extends up to the zick-zackfolded portion or into the zick-zack folded portion.
 6. The airbagaccording to claim 5, wherein the zick-zack folded portion comprises aplurality of folding lines, wherein the pre-folded portion extends atleast up to the folding line which has the least distance to therollfolded portion.
 7. The airbag according to claim 1, wherein thepre-folded portion is formed by folding the airbag along multiplefolding lines such that the pre-folded portion comprises at least threefolded subsections adjoining each other.
 8. The airbag according toclaim 1, wherein the airbag is formed by two airbag layers connected toeach other along at least one circumferential seam such that thepre-folded portion comprises at least four sections of airbag layersfolded on top of each other.
 9. The airbag according to claim 8, whereinthe two airbag layers are connected to each other in a portion, whichcontinues at least approximately along the folding line.
 10. The airbagaccording to claim 9, wherein the two airbag layers are connected toeach other via a tear seam and/or a glue seam.
 11. The airbag accordingto claim 1, wherein the pre-folded portion extends at least essentiallyover the complete length of the airbag.
 12. The airbag according toclaim 1, wherein the folding line and a roll axis of the roll foldingcontinue at least approximately parallel to each other.
 13. The airbagaccording to claim 1, wherein the folding line and a roll axis of theroll folding are oriented to each other in an angle.
 14. The airbagaccording to claim 1, wherein the airbag is a side airbag which extendsalong a vehicle longitudinal side in respect to the in the vehicleinstalled and inflated status.
 15. A method for folding an airbag for avehicle occupant restraint system for a motor vehicle comprising thesteps: Providing an evenly spread airbag; Generating a pre-foldedportion of the airbag by folding a subsection of the airbag about afolding line to an inner side of another subsection of the airbag facingthe vehicle interior space in the mounted and inflated status of theairbag such that the pre-folded portion comprises at least twosubsections of the airbag, Wherein the folded subsection is formed suchthat it extends beyond a door balustrade of a vehicle longitudinal sidein the mounted and inflated status of the airbag; and Generating a rollfolded portion of the airbag which comprises the pre-folded portion, byrolling up the airbag to an outer side of the airbag facing a vehiclelongitudinal side in the mounted and inflated status of the airbag,Wherein the folding line is positioned such that the pre-folded portionextends at least in a section of the airbag over the complete rollfolded portion.